乾旱嚴重度－延時－頻率曲線發展與應用：以曾文－烏山頭系統為例

Development and Application of Drought Severity-Duration-Frequency Curves: A Case Study in Tsengwen-Wusanto Reservoir System

范保國(Quoc Bao Pham) ； 陳仲廷(Chung-Ting Chen) ； 郭振民(Chen-Min Kuo) ； 楊道昌(Tao-Chang Yang) ； 游保杉(Pao-Shan Yu) ； 曾宏偉(Hung-Wei Tseng)

《農業工程學報》 66卷2期 (2020/06) Pp. 1-11

https://doi.org/10.29974/JTAE.202006_66(2).0001

摘要

臺灣於水資源規劃與檢討一般常以缺水指數作為依據，惟其計算上係基於年缺水率，因此難以反應枯水期情況，為能合理探討臺灣水資源系統於枯水期間之缺水特性，本研究嘗試導入乾旱SDF曲線（severity-duration-frequency curves）描述乾旱事件嚴重度、延時以及頻率年之關係，詳細說明其產製流程與分析結果，並以曾文-烏山頭水庫系統為例，研提可能之延伸應用方式，包含：連結歷史水文乾旱、乾旱衝擊評估以及枯水期間供水缺口評估，總結重要成果如下：（1）藉由點繪2014至2015年水文乾旱造成之缺水事件至現況條件下乾旱SDF曲線，得知其約莫為10年發生一次之大旱；（2）莫拉克颱風導致之泥砂淤積，造成多數延時與頻率年對應缺水事件之缺水率增加約1.5至6.0%；（3）基於現況條件下評估枯水期間供水缺口，發現其缺口相當於每日2.4萬噸（現況需水量每日約40萬噸），可作為未來枯水期間水源規劃上參考。

關鍵字

乾旱SDF曲線 ； 乾旱特性 ； 水資源規劃與管理

並列摘要

In Taiwan, the shortage index is usually used as the criterion for water resources planning purposes. However, the index calculation is based on annual water deficient ratios, which might underestimate the magnitude of drought events. In order to reasonably quantify properties of drought events during dry seasons, this study developed drought severity-duration-frequency (SDF) curves to interpret the relation between severity, duration and frequency of drought events. Details of development of drought SDF curves were provided and Tsengwen-Wusanto reservoir system was selected as the study area to demonstrate potential applications of drought SDF curves, including mapping of historical hydrological drought events, drought impact assessment and water shortage evaluation during dry seasons. The important findings are given as follows: (1) The 2014-2015 hydrological drought event was mapping onto the current drought SDF curve. The mapping results show the return period of the event is around 10 years; (2) Typhoon Morakot caused serious sedimentation problems and led to overall water shortage rates of drought events for various durations and return periods increased in a range from 1.5% to 6.0%; (3) The results of water shortage evaluation suggest that there is a 24,000-ton gap between water supply and water demand (the water demand is around 400,000 ton per day). The gap could be taken into account for future water resources planning and management during dry seasons.

並列關鍵字

Drought severity-duration-frequency curves ； Drought properties ； Water resources planning and management